2016/08/25 (Thursday)
| Setup: iZIP mode, DIB1/2/3 → 3.2 MHz filters → cables → DCRC55(1)/33(2)/50(3), Tower has been cooled below Al transition with mu-metal shield 37.8cm below standard position | |
| DCRCs powered overnight. Pumping on IVC with turbo pump overnight. Baked detector for 12 hours overnight, Tower at 0.4 K until 04:53. DCRC3 phonon channels are set for HV setup, should revert these before running in iZIP mode |
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| 0840 | Tower/MC/Coldplate = 38.8/37.0(?)/155 mK, Still = 1.33 K / 85 μbar, G1/G2 = 185/170 mbar, 1K Pot = 1.52 K / 4.0 mbar, MB = 42.6%. Boiloff rate: good |
| 0845 | Fill LN2 cold trap bath. |
| 0850 | Close turbo pump valve so that we are no longer pumping on IVC This is to maybe accelerate He buildup in IVC to see whether HV properties are affected |
| 0855 | IVC = 5.4 nbar |
| 0910 | Turn off trigger, tower, and DCRC programs on MIDAS, disconnect telnet DCRC sessions, unpower DCRCs. |
| 0915 | Set up HV mode, DIB1/2/3 → 3.2 MHz filters → nothing/disconnector board/remapping board → HVside2board → DCRC55(1)/50(3). Disconnector board has all charge lines disconnected. |
| 0915 | Power up DCRC1&3 and initiate telnet sessions, disable DCRC2 in ODB. |
| 0915 | Tower stable at 38.1 mK |
| 0916 | Zapping squids. |
| 0945 | Begin more breakdown tests. We'll use DCRC1pC to monitor breakdown. Define a baseline shift of >= 0.2 V as breakdown. Use overshooting: increase bias until pulses disappear, wait one minute, then reduce bias until baseline shift < 0.2 V. |
| 0950 | IVC = 7.4 nbar |
| 1000 | DCRC1pC baseline = -0.752, so breakdown condition will be baseline >= -0.55 V. |
| 1010 | Increase HV to 34.6 V (Vleak 48.3 mV): pulses disappear. After a minute pulses reappear with high noise, baseline 0.3 V. Attempt to lower bias until baseline below -0.55. But we went lower than necessary, after a minute pulses were very clean… repeat… At HV = 32.0 V, Vleak = 42.3 mV, after 1 minute, baseline = -0.64 (shift = 0.11) noise low. Breakdown limit: Vcrystal = +13.4 V |
| 1030 | Increase HV to -28 V, Vleak = -39 V: pulses disappear. Reduce to -20 V, -25.5 mV. Baseline = -0.69 V, noise very low. Breakdown limit: -8.8 V |
| 1031 | Over the last ~10 minutes tower temp has risen from 38mK to 40mK. Charge traces have some uncharacteristic noise. |
| 1032 | Reduce bias to 0V, charge noise and tower temp unchanged. Still at 0V, change bias polarity from negative→positive→negative by switching banana plugs at HV source back and forth. |
| 1032 | Charge noise seems fixed, traces look reasonable, tower temp falls to 39mK. |
| 1054 | Increase bias to -30V. DIB1PC completely gone, QI looks good still. Tower = 38.4mK. |
| 1105 | Phonon pulses slowly returning with lots of noise. Attempt to quickly de-neutralize detector by flashing while biased. Use ODB to turn on LEDs for ~2sec. |
| 1108 | Tower temp peaks at 160mK. |
| 1120 | Tower temp = 38.9mK, Phonon pulses return, but still have breakdown noise as before. V_leak=-37.2mV. Flashing seems to have done nothing… |
| 1127 | Begin warm up. Close V6. |
| 1135 | V6 closed. Close V13B and turn off He3 pump. Turn on MC Heater to 1.0mW. |
| 1145 | Lower mu-metal shield to 27.7 cm below standard position |
| 1155 | Tower jumps from 1.1 K → 3.1 K, IVC jumps to 250 nbar. G1 bottoms out at 30 mbar and begins to rise |
| 1200 | Tower = 3.4 K, IVC = 300 nbar. Open turbo pump valve to pump on IVC again. Turn off MC heater. |
| 1210 | G1 peaks at 150 mbar and starts to fall. Tower falling, currently 3.0 K |
| 1230 | Tower temp = 2.3K, G1 = 65mbar. Turn on He3 pump and open V13B. |
| lunch break… | |
| 1400 | V6 = 13.8%. Still pressure falls into readable range. G1/G2 = 180 mbar. Tower = 1.4 K. |
| 1455 | Open V6 all the way. |
| 1514 | Commence LHe transfer (33.6%). |
| 1630 | End LHe transfer(84.7%). |
| 1640 | Tower = 36.6 mK. Note that the DCRCs were off during the cooldown process. G1/G2 = 175/155 mbar, 1K Pot = 1.50 K / 5.0 mbar, Still = 85 μbar. |
| Detector has been cooled below Al transition temperature with mu-metal shield 27.7 cm below standard position | |
| 1640 | Raise mu-metal shield to standard position |
| 1642 | Return to iZip setup: iZIP mode, DIB1/2/3 → 3.2 MHz filters → cables → DCRC55(1)/33(2)/50(3) |
| 1644 | Power on DCRCs. Set up timing link. |
| 1646 | On ODB, enable DCRC2 and restore DCRC3 phonon settings to iZip values from HV mode values. |
| channel | lockpoint | SQ bias | QET bias |
|---|---|---|---|
| DCRC3B | -3.72 | -81.2 | 107 |
| DCRC3C | -1.7 | -70.0 | 86 |
| DCRC3D | -4.5 | -82.6 | 130 |
| 1651 | Tower = 37.7mK. Zapping squids. |
|---|---|
| 1728 | Release pressure from main bath. |
| 1752 | DIB1,3 Phonons look good. Everything (Q&P) on DIB2 super railed. Power cycle DCRC2. |
| 1752 | DIB2 looks better, except DIB2PB, which looks |
| 1757 | Fill LN2 cold trap full. |
| 1805 | Start 12-hour bake. |